Long in the tooth: Greenland shark named longest-living vertebrate

By Susan Scutti, CNN

Updated 12:17 PM ET, Fri August 12, 2016

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Photos:The longest-living animals on Earth

Greenland shark – Greenland sharks, which live an average of at least 272 years, rank as the longest-lived vertebrates on Earth, a new study indicates; they may live beyond 400 years. The joys of a long life are surely countless, but there's one small hitch: These sharks do not achieve sexual maturity until 150 or so. These natives of the North Atlantic Ocean can grow to be 21 feet long and 2,000 pounds. Blind due to the many parasites crowding their eyes, these sharks are said to have an impeccable sense of smell, which they make ample use of when they hunt.

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Photos:The longest-living animals on Earth

Tuatara – Tuatara, which live on 32 offshore islands of New Zealand, are the only surviving species in an ancient order of reptiles that lived during the age of dinosaurs. They tip the scales at 2 pounds or less, according to Encyclopedia Britannica. They can live more than 100 years, with most arriving safely at 60 -- an age that does not stop some females from continuing to reproduce. The tuatara's bite is strong, with a single row of teeth in its lower jaw fitting into a groove between two rows of chompers in its upper jaw. Though this reptile has no ears, it can hear, and though it has three eyes, only two can see.

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Photos:The longest-living animals on Earth

Immortal jellyfish – The turritopsis nutricula (dohrnii) species of jellyfish lives a normal life, but when a crisis arises, it can transform itself into a younger state. This process, known as "transdifferentiation," renders the jellyfish into a bloblike cyst, according to a 2003 study. Eventually, the blob becomes a colony of polyps, and from there, "it" can spawn hundreds of genetically identical copies of itself. Hence, this pinky-nail-size being is commonly referred to as the "immortal jellyfish."

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Photos:The longest-living animals on Earth

Bowhead whale – Scientists estimate the lifespan of this whale species, which commonly roams the Arctic, to be more than 100 years. This calculation is based on analyses of eye tissue plus the recovery of stone harpoon tips in their blubber, the World Wildlife Fund said. Spanning 60 feet and weighing thousands of pounds, these whales can break through 7 inches of sea ice to reach air. Black skin is accented by a single white beauty mark on the lower snout, and the females are larger than the males.

After feeding, the bowhead whale comes to the surface of the water to rest.

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Giant tortoise – The old Spanish word "galapago" means "saddle," which describes the shape of a giant tortoise's shell --and became the term used by ancient explorers. This, then, is the origin of the name for the Galapagos Islands, where it is estimated upward of 20,000 wild tortoises live today, according to the Galapagos Conservancy. These turtles are big, averaging 475 pounds packed into just 4 feet. Uniquely, they have developed the ability to survive without food or water for up to a year, and as a result, they commonly live 100 years.

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Geoduck – Pronounced "gooey-duck," the Native American name of this clam means "dig deep": They generally burrow 2 to 3 feet into sand, gravel or mud. These unsightly clams, which can be found from Alaska to Baja California, average about 2½ pounds, though some have beefed up to more than 8 pounds. On average, geoduck attain full growth at age 15 and go on to live at least 168 years, according to Washington Department of Fish and Wildlife.

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Ocean quahog – It is common to find ocean quahogs aged 100 years or older, the Northeast Fisheries Science Center said. Scientists have recorded a maximum shell length of 5½ inches for this species of clam and estimate a maximum lifespan of 225 years. The bands around their shells, like rings within a tree, are marks of their age, researchers believe. A slower-growing clam, the ocean quahog usually requires two to four decades to fully mature. This clam has an extremely slow metabolism and low oxygen consumption, two factors that may contribute to long life.

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Koi – How disappointing to learn that these brightly colored beauties are just a version of the common carp ... and yet, unlike their relatives, these cold-water fish can live longer than 100 years. In fact, one celebrity koi, known as Hanako in its native Japan, died in the 1970s at the age of 226, some claim. Koi can grow longer than 3 feet and share an ancestor with goldfish. Though they can mate with their smaller cousins, they produce sterile offspring, according to a New Zealand science website, NIWA. Though revered in Japan as a symbol of success and wealth, these fish are thought to have originated in China. Koi are intelligent and can be trained to recognize a person who feeds them.

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Photos:The longest-living animals on Earth

Red sea urchin – Moving slowly along the bottom of the ocean, red sea urchins use their spines as stilts, according to Alaska's Department of Fish and Game. The largest of urchins, the red sea variety, can reach nearly 3 inches in spine length while its outer skeleton can grow to a diameter of more than 7 inches. Generally, by age 10, these urchins stop growing in diameter, though they may continue to slowly plump. Research suggests that red urchins routinely celebrate 100 birthdays, yet scientists estimate that some discovered near Vancouver Island may be twice that age. These creatures vary in color between a uniform red and dark burgundy.

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Antarctic sponge – A simple glance reveals the Antarctic sponge to be among the most primitive of animals. Yet these remote sea creatures have versatile feeding behaviors, can produce unique chemicals and can display complex developmental processes, according to the Australian Antarctic Division. Sponges grow extremely slowly in the low temperatures they inhabit. Along with other low-metabolism species, sponges enjoy long lifespans. In fact, researchers calculated one specimen to be 1,550 years old.

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African elephant – Rare aquatic species generally put land animals to shame in terms of lifespan, and yet the African elephant deserves mention. In the wild, this beast can live to be 70 years old, according to the World Wildlife Fund. African elephants can grow to more than 12 feet tall and can weigh in at about 14,000 pounds. For the most part, females are fertile between the ages of 25 and 45, while it takes males about 20 years to compete in the mating game and fulfill the biological imperative to pass on their genes. Tusks are grown by both the males and the females for self-defense.

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Story highlights

Researchers estimate Greenland sharks live at least as long as 400 years

These Arctic sharks reach sexual maturity around the age of 150, according to a study

(CNN)Swim aside, bowhead whales: Greenland sharks have stolen the crown as longest-living vertebrate on Earth. University of Copenhagen researchers estimated that these sharks live at least 400 years, nearly two centuries longer than the whales.

A student job with the Greenland Institute of Natural Resources inspired Julius Nielsen, lead author of the new study, to research the Greenland shark, which roams the chill waters of the North Atlantic. "I encountered the sharks here for the first time, and I was fascinated that so little were known about such large sharks," Nielsen said.

They are the largest fish native to Arctic seas, with adults typically measuring between 13 and 16 feet and females consistently outgrowing the males.

Still, their biology was mostly a mystery, explained Nielsen. "For example, their age was unknown but expected to be great," he said, based on studies from more than 50 years ago. The extremely slow growth rates of these sharks -- less than a centimeter per year -- suggested they must live for many years."

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So how do you discover the age of a mute primordial shark? Nielsen and his colleagues turned to radiocarbon dating.

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In the mid-1950s, the testing of thermonuclear bombs left a huge amount of radiocarbon in the atmosphere. It became incorporated in both terrestrial and marine food webs throughout the globe and so naturally entered the diets of animals and fish. In fact, radioactive isotopes in animal tissue reflect this "bomb pulse," which has become a well-established time stamp for age validation of marine animals.

To determine the age of Greenland sharks, Nielsen and his colleagues examined the eye lens nuclei of 28 females, caught during scientific surveys. "We were inspired to use the eye lens from other age determination studies conducted on whales," he said.

He and his colleagues estimated that the two largest sharks in the study, measuring a little more than 16 feet, 2 inches, and 16 feet, 5 inches, were 335 and 392 years old, respectively. Further analysis suggested the lifespan of Greenland sharks was at least 400 years, with sexual maturity reached around the age of 150.

"The biology and life history of the deepwater shark species is mostly unknown," said Cindy A. Tribuzio, a research biologist at the National Marine Fisheries Service. She explained that these "sleeper sharks" are notoriously hard to study and said attempts to determine their age have shown little promise. "This study on Greenland sharks appears to open a new avenue of study into aging these deepwater shark species."

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Though the age estimates cannot be proved -- only the sharks know for sure -- Nielsen said other evidence, including high levels of accumulated contaminants, supports the results.

"Our results demonstrate that the Greenland shark is among the longest-lived vertebrate species," concluded Nielsen.